Altitude measuring apparatus



Nov. 30, 1937. G. wUNscH ALTITUDE MEASURING APPARATUS 4 Sheets-Sheet 1 Filed NOV. 27, 1953 lnventor:

Nov. 30, 1937. G,WUNSH 2,100,706

ALTITUDE MEASURING APPARATUS Filed Nov. 27, 1933 4 Sheets-Sheet 2 In ventor:

a. WUNSCH 2,100,706

ALTITUDE MEASURING APPARATUS Filed Nov. 27, 1933 4 S hee ts-Sheet s Inventor:

4 4 sheet -sheet 4 Filed Nov. 2'1; 195:5

Fig.4

m w l i i M" h 2 x f w 2 m m 7 Patented Nov. 30, 1937 ALTITUDE MEASURING APPARATUS.

Guido Wiinsch, Berlin-Steg litz, Germany, as signor to Askania-Werke A. G. vormals Centralwerkstatt-Dessan nnd Carl Bamberg- Friedenau, a corporation of Germany Application November 27,1933, Serial No. 699,941 In Germany November 26, 1932' 7 Claims. (01. 13-4) (Granted under the provisions of sec. 14, act of March 2, 1927; 357 O. G.

This invention relates to altitude measuring and/or indicating apparatus, more particularly for use on aircraft.

Barometrical altitude measuring apparatus have proven unreliable and unsafe, particularly when landing in foggy, misty, rainy or snowy weather or when for any other. reason the visibility is poor, because the atmospheric pressure varies from time to time and also with the locality, so that indications of the altitude of an aircraft by such apparatus are at best only approximately correct.

To remedy this disadvantage it has been prothe barometrical altimeter the pilot is obliged to A divide his activity and attention, at the very momerit when he should devote his entire attention and skill to effecting a safe landing. Furthermore it will be readily seen that some time must necessarily elapseibetween the time of-making the sounding apparatus reading and that of correcting the barometrical altimeter to correspond thereto. However short such time may be, the

aircraft will meanwhile have changed its altitude by several meters, thereby injecting a further source of error into the determination of the altitude. A

The present invention has forits object among other things, tp overcome these and other objections to the methods heretofore used and to provide apparatus that shall give the correct altitude at any and all times, and this by so combining suitable altitude measuring means or other means responsive to changes in atmospheric pressure, with a sounding apparatus of the echo-measuring type, for example, that both of said apparatus can control or operate a common altitude indicator means. Any suitable sounding apparatus of the general type referred to may be used in accordance with my invention, but I preferably use that type comprising a time measuring device running at constant speed, and, in which an index or pointer is set in motion when a wave train, preferably a sound wave train ls'sent out and would normally be arrested by action of the returning echo wave, so that from the distance covered by said index or pointer the echo period, and hence the correct altitude above the ground can be determined. 5 In carrying out my invention, however, the movement of said index or pointer is not arrested by the action of the returning echo wave, but is connected to the operating mechanism or driving gear of the means responsive to changes in atmosl0 pheric pressure, so that, upon completion of the altitude measurement by said sounding apparatus, said index or pointer of the time measuring device of said sounding apparatus will be controlled or moved by the mechanism of said 15 means responsive to changes in atmospheric pressure, the latter thus giving all further altitude indications thereafter. As said means responsive to changes in atmospheric pressure has then been automatically corrected by said echo measurement, for the atmospheric pressure actually existing at the landing place, the apparatus embodying my invention will. at all times indicate correct altitudes at the place of landing, thus relieving the pilot from the necessity of giving his attention to anything other than that of landing. While any suitable means responsive to changes in atmospheric pressure may be used within the scope of my invention,I preferably use onehaving an aneroid-like operating mechanism, and if it operates with diaphragm chambers, this is made possible by connecting the interior of said diaphragm chambers with a container of greater capacity which can at will be caused to communicate with or cut off from the atmosphere by a valve, or other suitable means. The echo measv uring' means having been set in operation on emission of a wave train, said valve will be closed at the instant said echo measuring means receives the return train of waves. Thereupon said dia- 40 phragm chambers will respond to any variation of the atmospheric pressure from that which obtained at the time. said wave train was emitted,

so that by using a scale having divisions in terms of altitude, the pointer or index of said time measuring device, being connected to the mechanisms of said barometrical altimeter by action of the returning wave train, will indicate real altitudes upon said scale.

The invention and its aims and objects will be .readily understood from the following description, taken in connection with the accompanying drawings, of two embodiments of the invention, herein given for illustrative purposes, the true scope of the invention being pointed out in the; appended claims. 1

In the drawings: I r Fig. 1 is a diagrammatic representation of one illustrative embodiment of the invention, certain parts being shown in section;

Fig. 2 shows diagrammatically another illustrative embodiment of the invention, certain partsbeing represented in section.

Fig. 3 shows in greater detail the structure only diagrammatically illustrated in Fig. 1.

- Fig. 4 is a perspective view of the shown 4 in Fig. 3.

Referring to Fig. 1, an echo measuring device of conventional construction and its time measuring device running at-constant speed are diagrammatically represented at 2. 4 is the index or pointer of said time measuringdevice, said index or pointer being mounted upon a shaft .6

which carrieslan iron disk I. A worm It, driven by any suitable driving means, for example by a regulated electric motor (not shown) meshes with a worm wheel l2. Said shaft 6 is freely-ro responsive to changes in atmospheric pressure,

which comprises essentially a diaphragm chamber system 24, herein comprising for example two diaphragm chambers, of which the diaphragms communicate their movements through a link 26 and an arm I" to a shaft m mounted in bearings 22, 32. The rotary movement communicated to the shaft I" is transmitted to,the shaft 22 through an arm I58 secured at one end upon the shaft I", the otherend of said arm I acting upon one end of-a lever 34 fulcrumed at "and having its other end provided with a toothed segment Ill which engages agear I42 fast upon the end of said shaft 22. ,Energizlng current is supplied to the magnet l2 through contacts 42, 44 engaging rings l4 and I8 and to magnet 20 through conductors 48, 42. Said energizing current will be supplied from any suitable source not shown. v

The above described ,embodlment operates as follows: 7 'Ihepointer4remainsat0untilanexactecho measurement is to be made. When this is to be done the operating mechanism of the echo measuring means is set in operation and when the wave train is emitted the circuit comprising contacts. 42 and 44 will be closed'by suitable means diagrammatically shown at illithus supplying the magnet I! with current, so that the said magnet attracts the disk 8 fast on said shaft 8 and causes itand said shaft I to rotate therewith atconstant speed, thus moving the index 4 over the scale. The returning wave train closes the circuit of the magnet 20 comprising conductors 48 and 48 by the operation of suitable means diagrammatically indicated at 52, so that the-magnet 20 being now energized attracts the disk I. As said magnet 20 is carried by the driving shaft 22 of the means responsive to .changes in atmospheric pressure, said index 4 from this time on will becontrolled or moved by operation of the .diaphragm chambers 24,through the mechanism above described. As said index had been previously adjusted by the operation of the echo measuring means to indicatethe correct altitude of the aircraft above the ground, said. index in its'continued movement'from now on-will indicate corrected altitudes, assuming that the ratio of said means responsive to changes in atmospheric of said means responsive to changes in atmospheric pressure correspond.

The interior of the diaphragm chambers 24 communicates preferably by means of pipes 54 and 56 with the interior of a container II, the interior capacity of which is relatively large as compared: to the interior capacity of said dia- I phragm chambers. A valve Cl provided in the pipe serves to close oil. communication of the container 58 with atmosphere or to establishsuch communication. Preferably said valve II will remain open when the apparatus is not in use, and closed only at the instant the echo measurement is'effected. The diaphragm chambers then operateaccording to the difference existing'from time to time between the atmospheric pressure and that atmospheric pressure which obtained at that point where the aircraft was at the moment that the echo measurement was made.

Referring to Figf2, in'th'e illustrative embodlment of the invention therein shown, the echo measm'ing means and diaphragm chamber of the means responsive to changes in atmospheric v pressure act through a diflerential drive. To this end, the shaft 8 of the timemeasuring device of the echo measuring means carries besides the pointer 4'-or in addition to the latter, a gear I2 which meshes with'a rack i4. Said rack 4 is pivotally connected at I to one end of a lever ll,

. the other end ll of whichds pivotally connected to one end of a link I2. The other end of said link 12 is acted upon by a spring member 14 which is moved through a contact member ll acted upon by moment of the diaphragm 18 of a diaphragm chamber ll of the means responsive to changes in atmospheric pressm'e. A link 82 connects a rack 24 with the center 28 of said lever II.

Said rack 24 meshesfwith a gear ll secured upon" the mart a which carries the index or pointer 22 of an altitude indicating means. The interior of a container 28 communicates with the interior of said diaphragm chamber I] through pipes 04 and 96. A valve Ill serves to establish or interrupt communication of said container II with atmos phere. r

so long as the valve ill remains open and the time measuring device of the echo measuring device is at rest no movementwill be imparted to the lever mechanism above described nor to ,the index '2. If,the'time measuring device be now set in operation by emission of a wave train, then said rack '4 will be moved in,the one or the other direction, say for example to the right, thus arrests the rack 4. Upon closure of the valve I III, the diaphragm chamber I alone acts upon the lever 62 through .link 12, said lever being now swung about the fulcrum I. From now on, therefore, the means responsive to changes in atmospheric pressure alone controls movement .or

adjustment of the pointer 32, so that the'latter indicates altitudes corrected automatically by the echo measuring means.

Referring to Fig. 3, I 20 is the driving motor opgether with a pot-shaped electromagnet I34, said shaft I32 being driven so 'as to revolve at constant speed. Said electromagnet I34 receives its current from battery I36 over line I38, I40 upon closure of relay switch 242. In front of said electromagnet I34 is placed a further electromagnet I44, also pot-shaped and rigidly keyed on a hollow shaft 6 shown in Fig. 4. .This hollow shaft I46 carries a gear I48 which meshes with a toothed segment I50 rotatable upon a .shaft I52 and connected with shaft I58 by levers I54, I56. Said shaft I58 is connected with diaphragm chambers I64 of the barometrical altimeter by a lever I60 and link I62. The interior of said diaphragm chambers I64 communicates with the atmosphere by a pipe I66 through valve I68 and with a container I12 by a pipe I10.

The winding of magnet I44 is supplied with current from battery I14 over the lines I16, I18 when switch I80 is closed.

Said gear I30 meshes with a gear I82,rigidly keyedon shaft I92 with cam disks I84, I86, I88.

In explaining the operation of the invention with reference to diagrammatic Figures 1 and 2, it was shown that before setting in operation the apparatus, both magnets I8 and 20 are left ourrentless and that upon emission of an. echo wave, magnet I8 is supplied with current, whereas the returning echo wave provides magnet 20 with current, at the same'time breaking the circuit of magnet I8. Inactual practice, however, such a simple switching would cause difiicultiesowing to the presence of remanent magnetism. It could happen that upon opening the circuit of magnet I8.and switching on current to magnet 20, the remanent magnetism in theiron of said magnet I8 wouldretard the shifting of the couplingof disk 8 from said magnet I8 to said magnet 20, thus giving rise to a false indication. In practice, therefore, a difierent method of connection is used which is commonly employed in echo sound meters; this method of connection comprises supplying both magnets with current shortly before the emission of a sound wave, the

fixed magnet being first supplied and shortly thereafter the magnet connected to the motor.

The iron disk connected with the pointer is consequently attracted by the fixed magnet and remains s9 attracted after the magnet on the motor shaft has been supplied with current. Simultaneously with the emission of the sound wave the current of the fixed magnet is switched off, thus practically simultaneously causing the mag "net of the motor to attract said disk, so that 'current,'but this effects no change, as the iron disk is still attracted by the first, rotary magnet. When, however, the microphone catches the re- -turning echo wave, the current for the motor rotated magnet is'switched oil over an amplifier relay arrangement to be described later on. Consequently the disk 8 is once againattracted to the fixed magnet with practically no delay whatever, thus arresting the pointer connected to the iron disk practically simultaneously with the arrival of the echo wave.

Referring to the diagram of the connections as illustrated in Fig. 3, the individual switching operations .in the embodiment of the invention are carried out in the same manner as is usually done in known echo sound meters. When the measurement is to begin, contact I2I, for example, is closed by hand, so that the motor I20 and magnet I34 will rotate. together as well as the cam disks I84, I86, I88 by the operation of gears I28, I30 and I82. The cam disks are adjusted relatively to each other on their shaft and are timed to operate as follows:

First of all contact I80 remains closed, thus supplying current to electromagnet I44, which is a fixed magnet in known echo meters, but in accordance with the present invention is positively connected to diaphragm chambers I64. Consequently the iron disk 2I0 will be attracted by said magnet I 44. On further rotation of the motor, however, cam I 86a of disk I86 closes contact 2I4, thus supplying current to the winding of relay 2I6 through conductors 2I8, 220 of battery 22I and through conductor 222, through amplifier 223 and conductors 224 and 226. Consequently both armatures 228, 230 are attracted thus closing contacts 242 and 244 and contact 242 connects magnet 260 to battery I36, whereby lever am 262 is attracted by saidmagnet and opens valve I68. On further rotation of the motor,

however, said cam. I86areleases immediately switch 2I4, thus breaking the circuit. Nevertheless, the winding of said relay 2I6 retains current, as said contact 224 had previously been closed and the current now flows from battery 22I over conductor 222, amplifier 223, conductor 224,

winding 2I6; conductor 226, switch contact 244, and conductors 2| 8, 220. Therefore, contact 242 also remains closed, magnets I44 and I34 con tinuing thus to be supplied with current. As, however, magnet I44 was first supplied with current, disk 2L0 remains attracted by said mag.-

net and pointer 2I2 therefore remains at rest.

1y, simultaneously with the opening of said contact said iron'disk 2I0 is attracted to said magnet =I34 which is still supplied with current, so that now pointer 2I2 is rotated, since said magnet is positively coupled to. the motor. At the same time, however, the circuit for magnet I44, just opened as above described, is reclosed by the left rim of saidslot I 84a, so, that both magnets I44 and I34 are instantaneously supplied with current. upon the emission of the sound wave and the setting in operation of pointer 2I2. As, however, before the magnetization of magnet I44, the magnet I34 was already supplied with current, disk 2I0 remains attracted by magnet I34, so that the pointer continues its movement. The returning echo wave is caught by a microphone 250, to which an amplifier 223 is so connected that the current of said microphone, influenced by the sound wave, weakens the amplifier current in consequence of its audion switching. As

this current flows through winding 2 I6 01 the relay over contact 244 to battery 22l, the relays induction is so far weakened that the relay drops its armatures 228 and 230 biased by springs 252 and 254 whereby contacts 242 and 244 are broken at the same moment at which the echo wave is received by microphone 250, thus leaving the anode current-in amplifier .223 interrupted, so that relay 2H5v remains inactive. The opening of contact 242, however, has rendered magnet I34 currentless simultaneously with the returning echo wave, so that at the same moment the iron disk is attracted to magnet I44, thus positively connecting pointer 2l2 with said diaphragm chambers I64. Both conductors 256, 258, leading to the winding of the magnet 260 are, however, branched ofl from lines I380, 140. The armature of said magnet 250 consists of the right arm 252 of a two-armed lever, the other arm 01' embodied in other specific forms than those herein., described without departing from the spirit or essential attributes thereof, and I therefore desire the present embodiments of said invention to be considered in all respects as illustrative and not restrictive, reference being had to the appended claims rather than to the foregoing description to indicate the scope of the invention.

1. Apparatus oi the class described comprising I an aneroid diaphragm having a valve controlling means communication with the atmosphere; indicating means; a constant speed rotor; motion transmission means, including a clutch mechanism selectively to connect said aneroid diaphragm and said constant speed rotor with said indicating means; means to emit a wave train; means simultaneously operable at the time of emission of the wave train to control said clutch mechanism to connect said indicating means with said constant speed rotor; means responsive to'the return wave train to control said clutch mechanism to disconnect said indicating means from said constant speed rotir and connect said means with said aneroid diaphragm, said responsive means also controlling said valve to shut of! communication of said aneroid diaphragm with the atmosphere.

2. Apparatus of the class described comprising,

in combination, means to emit a wave train; a

- shaft revolving at constant speed; altitifde indicator means; means rendered operative to connect said altitude indicator means to said shaft upon emission of a wave train and to disconnect it therefrom upon return of said wave train after reflection from the ground; means responsive to changes in atmospheric pressure; and means operative to connect said means responsive to changes 01' atmospheric pressure to said indicator vice after reflection from the ground.

3. Apparatus of the class described comprising,

upon return of said wave train tosaid dein combination, means to emit a wave train; means operated at constant speed; altitude indicator means; means rendered operative by emission of a wave train to connect said altitude indicator means to said means operated at constant 5 speed and to disconnect said altitude indicator means from said means operated at constant speed upon return of said wave train after reflection from the ground; means responsive to changesin atmospheric pressure; and means 1( operative to connect said means responsive to changes in atmospheric pressure to said indicator means, upon return of said wave train after reflection from the ground.

4. Apparatus of the class described comprising, 14

in combination, means to emit a wave train; altitude indicator means; driving means adapted to ,drive said altitude indicator means at constant speed; means responsive to changes of atmospheric pressure; and means responsive to the 24 return of the wave train to disconnect said altitude indicator means from said driving means and connect said altitude indicator means to. said means responsive to changes in atmospheric pressure. 24

5. Apparatus of the class described comprising, in combination, means to emit a wave train; altitude indicator means; driving means adapted to drive said altitude indicator means at constant speed; means responsive to changes in atmos- 8i pheric pressure; a clutch; means actuated on emission of a wave train to operate said clutch to connect said driving means'to said altitude indicator means; and means actuated by said wave train upon its return after reflection from a the ground to operate said clutch to disconnect said driving means from said altitude indicator means and to connect said altitude indicator means to said means responsive to changes in atmospheric pressure for operation by the latter. 4

.nect said constant speed means from and connect said pressure responsive means to said differential gearing. t '7. Apparatus of the class described comprising, in combination, altitude indicator means; means responsive to changes in atmospheric pressure,- means traveling at constant speed; a diflerential gearing alternatively operable by said pressure responsive means and said constant speed means and connected to actuate said indicator means; means to emit a sound wave-train, said constant speed means being connected to operate the differential gearing at the instant of emission of a sound wave train; and means responsive to the return of the sound wavetrain to render the constant speed means inoperative on the diflerential gearing and to render the pressure responsive means operative on the differential gearing.

aomo' wtinscn; 

